CVE-2026-77555Network attack vector

Service interruption via out-of-bounds write

Published Sep 22, 2026 · Updated Sep 22, 2026

An out-of-bounds write in Ubiquiti UniFi gateway devices allows remote attackers with network access to interrupt service. Ubiquiti has not published the affected component or the input whose processing writes beyond memory bounds. Exploitation requires network reachability but no authentication or user interaction, and the reported consequence is service interruption.

CVSS severity7.5
High
EPSS probability0.46%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds write in Ubiquiti UniFi gateway devices allows remote attackers with network access to interrupt service. Ubiquiti has not published the affected component or the input whose processing writes beyond memory bounds. Exploitation requires network reachability but no authentication or user interaction, and the reported consequence is service interruption.

The record

CVE
CVE-2026-77555
Published
Sep 22, 2026
Updated
Sep 22, 2026
Vendor
Ubiquiti
Product
Cloud Gateways
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <5.1.31

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Ubiquiti · Cloud Gatewaysversion=0 <5.1.31
Ubiquiti · UniFi Express 7version=0 <5.1.31
Ubiquiti · Dream Routersversion=0 <5.1.31
Ubiquiti · UniFi Gatewaysversion=0 <5.1.26
Ubiquiti · Dream Wallversion=0 <5.1.31
Ubiquiti · Enterprise Firewallsversion=0 <5.1.31
Ubiquiti · Dream Machinesversion=0 <5.1.31
Ubiquiti · UniFi Expressversion=0 <4.0.21

Published CVSS scores

7.5Ubiquiti Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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